1. Field of the Invention
The present invention relates to a level sensor and, more particularly, to a vehicle cesspool level sensor adapted to detect the level of dirty water in the cesspool of a motor vehicle.
2. Description of the Related Art
A conventional vehicle cesspool level sensor, as shown in FIGS. 4 and 5, comprises a mounting base 4, the mounting base 4 having a center mounting hole 41 and an outer thread 42, a strainer 6, the strainer 6 having through holes 611 evenly distributed over the periphery, an inner thread (not shown) provided at the top end and threaded onto the outer thread 42 of the mounting base 4, and an outer thread 61 provided at the bottom end, a perforated bottom cap 62 threaded onto the outer thread 61 of the strainer 6, a detection rod 5 fastened to the center mounting hole 41 of the mounting base 4 with glue and axially suspended inside the strainer 6, the detection rod 5 having a top end fixedly fastened to the center mounting hole 41 of the mounting base 4 and a bottom end capped with an end cap 51, a detection circuit 52 mounted inside the detection rod 5, and a float 53 coupled to the detection rod 5 and movable with the level of the dirty water in the cesspool of the motor vehicle along the detection rod 5, and a magnet 531 fixedly mounted in the float 53 and adapted to induce the detection circuit 52 inside the detection rod 5. The strainer 6 is formed of a plurality of strainer elements that are respectively fastened to one another by a screw joint.
This structure of vehicle cesspool level sensor is still not satisfactory in function because of the following disadvantages.
1. The detection rod 5 is fastened to the center mounting hole 41 of the mounting base 4 with glue to prevent a leakage. However, the glue deteriorates quickly with use. A sever vibration of the motor vehicle may cause the detection rod 5 to loosen from the mounting base 4, resulting in a leakage.
2. The end cap 51 is sealed to the bottom end of the detection rod 5 with glue. However, the glue deteriorates quickly with use, and dirty water tends to leak in the detection rod 5.
3. Because the strainer 6 is molded from plastics, it must have a certain wall thickness to provide the desired strength. However, the through holes 611 in the thick wall of the strainer 6 may easily be blocked with waste matter. It is complicated to clean the strainer 6.
4. In order to firmly secure the strainer elements of the strainer 6 together, a bonding agent is applied to the screw joint between each two strainer elements. After installation, the strainer elements of the strainer 6 are not detachable for washing.